Multi-carrier power pooling

ABSTRACT

Novel techniques for pooling the available transmit power of a beam across the subcarriers that are or that are scheduled to be in use (and not across all available subcarriers) are disclosed. The scheduled subcarriers may be located in the same or different carriers of a modulation transmitter modulation system, and the pooled transmit power may be allocated or distributed across the scheduled subcarriers of the beam. Modulation symbols or resource elements may be transmitted in accordance with allocated, per-subcarrier power budgets, thereby maximizing the SNIR of signals that are transmitted in the beam via the scheduled subcarriers. Additionally, the allocation of the pooled transmit power to various subcarriers may continuously and/or dynamically vary over time, e.g., based on traffic demands, interference characteristics, etc., as well as based on subsequent scheduling of subcarriers to transmit subsequent modulation symbols or resource elements.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to and the benefit of U.S.Provisional Patent Application No. 62/358,437 entitled “HybridAir-to-Ground Network Incorporating Unlicensed Bands” and filed on Jul.5, 2016, the disclosure of which is hereby incorporated by referenceherein in its entirety.

FIELD OF THE DISCLOSURE Technical Field

The instant disclosure generally relates to pooling transmit poweracross the subcarriers that are or that are scheduled, at a base stationor ground station, to be in use in a modulation system, such as amulticarrier and/or bandwidth adjustable modulation system, andmaximizing signal-to-noise-plus-interference ratio (SNIR) fortransmitted signals.

Background

The use of unlicensed spectrum for air to ground (ATG) communications isvery attractive to In-Flight Connectivity (IFC) providers as theunlicensed spectrum allows IFC providers to tap into free spectrum thathistorically has been used for terrestrial services only. In the UnitedStates, the unlicensed 2.4 GHz and 5 GHz frequency bands are used formany terrestrial applications such as cordless phones, hearing aids,baby monitors, etc., as well as for terrestrial local/short-rangecommunications systems such as Wi-Fi and Bluetooth. More recently,wideband, terrestrial cellular communications systems such as LTE(Long-Term Evolution) standard-based systems in the U.S. and otherjurisdictions are using unlicensed spectrum for terrestrial cellularcommunications between cellular phones, smart devices, and the like.

The use of unlicensed spectrum in the U.S. is subject to strictjurisdictional rules. For example, the Federal Communications Commission(FCC) rules define, for each transmitter operating in the 2.4 GHzfrequency band, maximum limits for its conducted or radiated power. Forinstance, per 47 CFR15.247 (c)(2)(ii), “ . . . the total conductedoutput power shall be reduced by 1 dB below the specified limits foreach 3 dB that the directional gain of the antenna/antenna array exceeds6 dBi,” and per 47 CFR15.247(c)(iii): “the aggregate power transmittedsimultaneously on all beams shall not exceed the limit specified inparagraph (c)(2)(ii) of this section by more than 8 dB,” and “[i]ftransmitted beams overlap, the power shall be reduced to ensure thattheir aggregate power does not exceed the limit specified in paragraph(c)(2)(ii) of this section.” These power limit requirements are definedper transmission beam within the total bandwidth of the 2.4 GHzfrequency band, regardless of how much frequency bandwidth is used bythe transmission beam. In other words, a beam transmitted in the 2.4 GHzfrequency band using 500 KHz of bandwidth is limited to the sameradiated power as a beam using 60 MHz of bandwidth.

The use of multicarrier modulation schemes like OFDM (OrthogonalFrequency-Divisional Multiplexing) in modern wideband communicationssystems allows systems to allocate different bandwidths to differentusers and to dynamically change the bandwidth allocations over time.Consequently, with OFDM, transmitters may be instructed to not useportions of the spectrum that could be subject to high interferencecoming from other users of the spectrum (e.g., Wi-Fi, Bluetooth, etc.).In a conventional LTE (Long-Term Evolution) standards-based systemutilizing OFDM, the total power per modulation symbol is bounded by thetotal allowed transmission power per carrier, and the power permodulation symbol is budgeted as a fixed, pre-configured amount, e.g.,the total power per carrier divided by the total number of configuredsubcarriers.

BRIEF SUMMARY OF THE DISCLOSURE

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter.

In an embodiment, a wireless communication system may include amodulation transmitter configured to wirelessly communicate with aplurality of user terminals via a plurality of carriers, where eachcarrier supports a respective plurality of subcarriers. The modulationtransmitter may support bandwidth adjustable modulation. For example,the modulation transmitter may support multicarrier modulation. Thewireless communication system may further include a controllerconfigured to determine a total number of subcarriers that are scheduledto be in use across the plurality of carriers, where the total number ofscheduled subcarriers is less than a total number of availablesubcarriers across the plurality of carriers. Additionally, thecontroller may be configured to allocate, based on the total number ofsubcarriers that are scheduled to be in use across the plurality ofcarriers, a respective portion of a per-beam power budget to eachsubcarrier that is scheduled to be in use across the plurality ofsubcarriers, the per-beam power budget being a per-beam power limit; andcontrol, in accordance with the allocated respective portions of theper-beam power budget, resource elements transmitted by the modulationtransmitter to communicate with the plurality of user terminals via thesubcarriers that are scheduled to be in use across the plurality ofcarriers.

In an embodiment, a method of maximizing thesignal-to-interference-plus-noise ratio (SINR) of wireless signalstransmitted to a particular user terminal may include, at a modulationtransmitter system, forming at least one beam included in a plurality ofnon-overlapping beams in a frequency band, where the frequency bandsupports a plurality of carriers, each beam is to transmit data to arespective user terminal, and each beam is subject to a per-beam powerlimit. The method may also include allocating, to the particular userterminal, a bandwidth of a particular beam of the plurality ofnon-overlapping beams, where the bandwidth of the particular beam isless than a total bandwidth of the frequency band; determining, based onthe bandwidth allocated to the particular user terminal and the per-beampower limit, a respective power budget for each resource element to betransmitted via the particular beam; and transmitting, to the particularuser terminal via the particular beam, a set of resource elements inaccordance with the determined respective power budgets. The modulationtransmitter may support adjustable bandwidth modulation, for example,such as multicarrier modulation and/or other types of adjustablebandwidth modulation.

In an embodiment, a method of maximizing thesignal-to-interference-plus-noise ratio (SINR) of wireless signalstransmitted to a particular user terminal includes determining, by acontroller, a total number of subcarriers that are scheduled to be inuse across a plurality of carriers included in a beam formed by amodulation transmitter, where the total number of scheduled subcarriersacross the plurality of subcarriers is less than a total number ofavailable subcarriers across the plurality of carriers. The method mayfurther include allocating, by the controller and based on the totalnumber of subcarriers that are scheduled to be in use across theplurality of carriers, a respective portion of a per-beam power budgetto each scheduled subcarrier, the per-beam power budget being a per-beampower limit; and controlling, by the controller in accordance with theallocated respective portions of the per-beam power budget, one or moreresource elements transmitted by the modulation transmitter via thescheduled subcarriers of the beam to communicate data with a particularuser terminal. The modulation transmitter may support adjustablebandwidth modulation, for example, such as multicarrier modulationand/or other types of adjustable bandwidth modulation.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of an example modulation ground station unitwhich may be utilized to pool transmit power and/or maximize the SINRsof wireless signals that are transmitted to in-flight aircraft;

FIG. 2 is a block diagram of an example aircraft unit which may receivethe signals transmitted by the modulation ground station unit of FIG. 1while the aircraft unit is in-flight;

FIG. 3 depicts an example conventional power allocation across rceblocks that are available for transmissions from a modulationtransmitter to one or more receivers;

FIG. 4A depicts an example power allocation across resource blocks thatare in use or that are scheduled to be in use for transmissions from amodulation ground station unit to one or more in-flight aircraft units,e.g., in accordance with at least some of the novel techniques describedherein;

FIG. 4B is a table illustrating how pooled power is assigned,distributed, or apportioned to the resource blocks of FIG. 4A;

FIG. 5 depicts a flow chart of an example method of maximizing thesignal-to-interference-plus-noise ratio (SINR) of wireless signalstransmitted to a particular user terminal or aircraft unit; and

FIG. 6 depicts a flow chart of an example method of maximizing thesignal-to-interference-plus-noise ratio of wireless signals transmittedto a particular user terminal or aircraft unit.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Although the following text sets forth a detailed description ofnumerous different embodiments, it should be understood that the legalscope of the description is defined by the words of the claims set forthat the end of this patent and equivalents. The detailed description isto be construed as exemplary only and does not describe every possibleembodiment since describing every possible embodiment would beimpractical. Numerous alternative embodiments could be implemented,using either current technology or technology developed after the filingdate of this patent, which would still fall within the scope of theclaims.

It should also be understood that, unless a term is expressly defined inthis patent using the sentence “As used herein, the term ‘______’ ishereby defined to mean . . . ” or a similar sentence, there is no intentto limit the meaning of that term, either expressly or by implication,beyond its plain or ordinary meaning, and such term should not beinterpreted to be limited in scope based on any statement made in anysection of this patent (other than the language of the claims). To theextent that any term recited in the claims at the end of this patent isreferred to in this patent in a manner consistent with a single meaning,that is done for sake of clarity only so as to not confuse the reader,and it is not intended that such claim term be limited, by implicationor otherwise, to that single meaning. Finally, unless a claim element isdefined by reciting the word “means” and a function without the recitalof any structure, it is not intended that the scope of any claim elementbe interpreted based on the application of 35 U.S.C. §112, sixthparagraph.

An in-flight connectivity (IFC) system may utilize various differentair-to-ground frequency bands to communicate data and signaling betweenterrestrial ground stations (e.g., ground or terrestrial base stations)and aircraft that are in flight. For example, data and signaling used bypilots and other on-board crew members to navigate, operate, control,and/or service the aircraft may be communicated between the aircraft andthe ground during flight. More recently, at least some of thecommunicated data transmitted between an in-flight aircraft and groundstations is for consumption by passengers or other users who areon-board the in-flight aircraft (e.g., text messages, media, streamingdata, website content, etc.). The data for consumption or content datamay be delivered from the ground stations to the aircraft via theair-to-ground frequency bands, and subsequently to an on-board networkfor delivery to personal electronic devices (PEDs) operated bypassengers or users on board the aircraft. Examples of air-to-groundfrequency bands utilized for various types of air-to-groundcommunications include the 849-851 MHz and 894-896 MHz bands in theUnited States, frequency bands utilized by ARINC (Aeronautical Radio,Incorporated) standards, and other direct air-to-ground frequency bandsthat are disposed directly between the aircraft and terrestrial base orground stations. Other examples of air-to-ground frequency bands includesatellite bands such as the K_(u), K_(L), K_(a), and S bands, whichrequire an intermediate satellite or other station to deliver data andsignaling between the aircraft and a terrestrial base or ground station.Additionally, whether direct air-to-ground frequency bands or indirect(e.g., using a satellite or other suitable intermediary) air-to-groundfrequency bands are utilized, various modulation schemes may be utilizedto deliver data between the in-flight aircraft and terrestrial groundstations, such as satellite protocols and/or mobile communicationsprotocols that are typically utilized for terrestrial cellularapplications, e.g., TDMA (Time Division Multiple Access), GSM (GlobalSystem for Mobile Communications), CDMA (Code Division Multiple Access),EVDO (Evolution Data Optimized/Option), LTE (Long Term Evolution), andthe like.

Generally speaking, conventional air-to-ground frequency bands (e.g.,849-851 MHz and 894-896 MHz bands, satellite bands, etc.) requirelicenses for operation therein. Thus, to supplement or augment in-flightconnectivity, IFC providers are looking to unlicensed spectrum via whichto transmit content data and signaling between terrestrial groundstations and aircraft. Examples of such options include the 2.4 GHzfrequency band and the 5 GHz frequency band which, in the United Statesand other jurisdictions, at least respective portions of are unlicensedand therefore may be utilized by many different terrestrialapplications, such as cordless phones, hearing aids, baby monitors,etc., as well as by local/short-range wireless communications systems(e.g., Wi-Fi, Bluetooth, etc.) and wideband terrestrial cellularcommunications systems such as LTE.

At least due to the wide range of applications that utilize unlicensedspectrum, its usage is subject to strict jurisdictional rules, includinglimits to transmitted power of beams. For instance, in the unlicensed2.4 GHz spectrum, per 47 CFR15.247 (c)(2)(ii), “ . . . the totalconducted output power shall be reduced by 1 dB below the specifiedlimits for each 3 dB that the directional gain of the antenna/antennaarray exceeds 6 dBi,” and per 47 CFR15.247(c)(iii): “the aggregate powertransmitted simultaneously on all beams shall not exceed the limitspecified in paragraph (c)(2)(ii) of this section by more than 8 dB,”and “[i]f transmitted beams overlap, the power shall be reduced toensure that their aggregate power does not exceed the limit specified inparagraph (c)(2)(ii) of this section.” These power limit requirementsare defined per transmission beam within the 83.5 MHz total bandwidth ofthe 2.4 GHz frequency band regardless of how much frequency bandwidth isused by the transmission beam. In other words, a beam transmitted in the2.4 GHz frequency band using 500 KHz of bandwidth is limited to the sameradiated power as a beam using 60 MHz of bandwidth.

Recently, wideband terrestrial cellular communications systems such asLTE (Long-Term Evolution) standard-based systems are starting to use the2.4 GHz spectrum for use in communicating to/from terrestrial cellularphones, smart devices, and other types of wireless user terminals orpersonal electronic devices (PEDs). Conventional, terrestrial-based LTEsystems operating in the 2.4 GHz frequency band typically utilize OFDM(Orthogonal Frequency Division Multiplexing), which is a type of digitalmulticarrier modulation scheme, for transmissions from terrestrial basestations to user terminals or PEDs. Generally, OFDM and other types ofmulticarrier modulation transmitters or transmitter systems wirelesslytransmit respective data to user terminals via a plurality of carrierswithin a frequency band. To optimize communications, a multicarriermodulation transmitter or transmitter system may transmit respectivedata to multiple user terminals by respectively modulating respectivestreams of bits or data into a constellation that is appropriate to orbased on the channel characteristics of each user terminal, andallocating the resulting modulation symbols to one or more carriers(and/or to subcarriers of the carriers) for delivery to the userterminal. For ease of reading herein, the description refers to aparticular type of multicarrier modulation, e.g., OFDM. However, it isnoted that any or all the techniques, methods, and systems discussedherein with respect to OFDM transmitters and schemes are equallyapplicable to other types of suitable multicarrier modulation types orschemes, such as Generalized Frequency Division Multiplexing (GFDM),Filter Bank Multi Carrier (FBMC), etc. Additionally or alternatively,any or all the techniques, methods, and systems discussed herein withrespect to OFDM transmitters and schemes are equally applicable tosuitable bandwidth adjustable modulation types or schemes other thanOFDM that are implemented on one or more carriers, as is explainedfurther below.

As discussed above, in the unlicensed 2.4 GHz frequency band, the FCCrules define the maximum radiated power level per beam (up to a givenmaximum number of beams). As such, the signal-to-interference-plus-noiseratio (SINR) (which may also be referred to assignal-to-noise-plus-interference ratio or SNIR) per user can bemaximized by transmitting the maximum allowed radiated power on eachbeam when each beam is assigned to service only one respective user.

However, in conventional terrestrial LTE/OFDM implementations, themaximum power that is radiated by a base or ground station is limited ona per carrier basis in accordance with LTE standards. Further, theamount of power that is budgeted to each subcarrier of a carrier ispre-configured and is the same for each subcarrier, e.g., power limitper carrier divided by the total number of available subcarriers. As iscommonly known, a “subcarrier” generally refers to a secondary channelthat resides within or is carried on top of a main channel, that is, acarrier within a carrier. The prefix “sub-” denotes that the subcarrieris related or derived from its corresponding carrier, however,typically, a subcarrier signal is modulated and demodulated separatelyfrom the main carrier signal.

At any rate, within conventional, terrestrial LTE/OFDM implementations,given the maximum per-carrier power limit and the pre-configured,per-subcarrier power limit, the use of a conventional LTE/OFDMtransmitter in the 2.4 GHz frequency band for in-flight air-to-groundconnectivity would result in a sub-optimal power distribution at leastbecause power limits would be budgeted based on a per beam/per carrierbasis, which is at odds with the greater distances between and higherlevels of interference observed by ground transmitters and in-flightreceivers (as compared to terrestrial base station transmitters and userterminals). In particular, conventional power budgeting of LTE/OFDMtransmitters cannot create sufficient power density for in-flightair-to-ground connectivity applications.

The novel systems, methods, and techniques described herein addressthese and other inefficiencies and inadequacies. Generally, the systems,methods, and techniques described herein continuously and dynamicallymaximize the SINR of signals transmitted from ground stations toin-flight aircraft. In an embodiment, the maximum power limit or budgetper transmission beam may be pooled, allocated, or distributed acrossthe number of subcarriers that are in use or that are scheduled to be inuse (e.g., in accordance with allocated user bandwidths), regardless ofthe particular carrier in which each in-use subcarrier is located. Thus,as the power budget is allocated amongst only resource blocks and/orrespective resource elements corresponding to subcarriers in use (ascontrasted with conventional power budget allocations that arepre-configured to be the same for all available subcarriers), theaverage power per resource element may increase over conventional powerallocation techniques. Moreover, as the novel systems, methods andtechniques described herein are not subject to a per-carrier powerlimit, the transmission beam power may be budgeted across all carriersutilized by the beam, thereby further increasing the average power perresource. As used herein, the term “resource element” generally refersto a particular, single subcarrier over the duration of a particular,single modulation symbol that may be used to transmit data, and the term“resource block” generally refers to a set of one or more subcarriersand a set of one or more modulation symbols that may be utilized totransmit data, for instance, a group of subcarriers and a group ofmodulation symbols.

FIG. 1 is a block diagram of an example modulation Ground Station Unit(GSU) 100 (also referred to interchangeably herein as a base station, amodulation transmitter, or a transmitter system) which may be utilizedto maximize the SINRs of wireless signals transmitted to in-flightaircraft. In FIG. 1 and elsewhere within this disclosure, for ease ofdiscussion, the modulation Ground Station Unit 100 is depicted anddescribed as a multicarrier ground station unit or transmitter that iscapable of transmitting over multiple carriers. However, any or all thetechniques, methods, components, features, and/or aspects of themulticarrier Ground Station Unit 100 discussed herein are equallyapplicable to ground station units that support other types of bandwidthvariable modulation, whether such ground station units transmit overmultiple carriers or over a single carrier.

The Ground Station Unit 100 may include a Base Band Unit (BBU) 102 andone or more Remote Radio Units (RRUs), each of which may be connected toa respective antenna 105 a-105 n. As illustrated in FIG. 1, the BBU 102may include one or more Base Band Processors (BBPs) or controllers 108a-108 n, each of which may control a respective RRU-antenna pair 105a-105 n. Generally, a BBP 108 a-108 n may perform baseband processingfunctions, such as frequency shifting, encoding, modulation, symbolforming, beam forming, etc. For example, a BBP 108 a-108 n may formsymbols based on a characteristic of a channel corresponding to a targetin-flight aircraft. The chassis of the BBU 102 may provide power,management functions, and a backhaul interface to the BBPs 108 a-108 n.In some embodiments, the BBU 102 may include a GPS antenna and receiver112, e.g., for synchronization functions.

Each RRU-antenna pair 105 a-105 n may perform the up conversion of thedigital data to a desired RF (Radio Frequency), as well as beam steering(and, in some scenarios, beam forming) of one or more respective beams110 a-110 m (which, for ease of illustration, are only shown in FIG. 1for the RRU-antenna pair 105 a). As such, each RRU may include one ormore respective processors or controllers. In an embodiment, each beam110 a-110 m may be steered in azimuth and elevation to establish apoint-to-point connection with a respective aircraft unit or receiver,and as such, each beam 110 a-110 m does not overlap with any other beam.Generally speaking, within the coverage range of the Ground Station Unit100, a single beam 110 a-110 m may service or steer the life of apoint-to-point connection between the Ground Station Unit 100 and atransceiver at a respective aircraft in order to maintain connectivityto the aircraft.

Thus, generally speaking, the beams 110 a-110 m may be non-overlappingbeams which may be formed, for example, by beamforming. In anembodiment, the non-overlapping beams 110 a-110 m may be defined byweighting modulation symbols with appropriate phases, thereby creatingnon-overlapping beams. Further, in some embodiments, the amplitude ofthe weights may be selected to refine the non-overlapping of the beams.

In an embodiment, the BBPs 108 a-108 n and respective RRU-antenna pairs105 a-105 n may be communicatively connected. Each BBP and RRU-antennapair may be referred to as a Ground Station Sector (GSS) 115 a-115 n,each of which may support a respective set of point-to-point connections(e.g., via respective beams 110 a-110 m). Each GSS 115 a-115 n mayoperate in a frequency band independently of other GSSs provided by theground station 100, and the respective coverage areas of the variousGSSs 115 a-115 n provided by the ground station 100 do not overlap. Inan embodiment, each GSS 115 a-115 n may form a wide beam that broadcastsa respective pilot signal that may be utilized by aircraft receivers forsector identification, channel sounding, etc. However, it is noted thatthe sectored implementation of the Ground Station Unit 100 illustratedin FIG. 1 is only one of many embodiments. For example, any number ofany of the techniques discussed herein is equally applicable to groundstation units that do not operate using sectors.

It is also noted that in FIG. 1, the Ground Station Unit 100 isillustrated as supporting n sectors or GSSs 115 a-115 n (i.e., nrespective BBP/RRU/antenna systems), where n may be any positive integersuch as 1, 2, 6, 10, etc. Additionally, RRU-antenna pair 105 a isillustrated as generating m beams, where m may be any positive integersuch as 1, 2, 4, 6, 16, etc. Further, different RRU-antenna pairs maygenerate the same or different respective numbers of beams. As such,given the flexibility of configuring different numbers of sectors (ifany at all), different numbers of RRU-antenna pairs, and/or differentnumbers of beams transmitted per antenna, various Ground Station Units100 may be engineered as desired to provide desired in-flightconnectivity coverage in different environments.

FIG. 2 is a block diagram of an example aircraft unit 120, which is alsoreferred to interchangeably herein as a user terminal. As illustrated inFIG. 2, the aircraft unit 120 may include a Customer Premises Entity(CPE) 122 that is fixedly attached to an aircraft and a power amplifier(PA)-antenna pair 128. The CPE 122 may include a base band processorcontrol unit and RF transceiver module (not shown), for example.Generally speaking, the CPE 122 may perform baseband processingfunctions and up conversion to RF, and the power amplifier (PA) mayboost the RF signal generated by the CPE 122 prior to radiating out theantenna aperture. Additionally, the CPE 122 may control the pointingand/or steering of the beam130 radiated by the antenna, e.g., in theazimuth direction and/or as desired. A single beam 130 may steer duringthe life of a point-to-point connection with a particular Ground StationUnit 100 in order to maintain in-flight connectivity, for example. Insome implementations, the aircraft unit 120 may include multiplePA-antenna pairs (not shown), e.g., corresponding to multiple airbornesectors, and the CPE 122 may select one of the antenna pairs to use forcommunicating with one or more ground stations 100.

The CPE 122 and the PA-antenna pair 128 may be communicatively connectedin any suitable manner, and the chassis of the aircraft unit 120 mayprovide power, management functions, and a backhaul interface to the CPE122. In some embodiments, the CPE 122 may include a GPS antenna andreceiver 132, e.g., for synchronization functions.

As discussed above, at least a portion of the frequency band(s) viawhich the Ground Station Units 100 and the aircraft units 120communicate may be unlicensed and thus subject to high interference. Inan embodiment, at least a portion of the frequency band(s) via which theGround Station Units 100 and the aircraft units 120 communicate may bethe unlicensed 2.4 GHz spectrum in the United States, and the conceptsherein are discussed with respect to said frequency band. However, it isappreciated that any one or more of the systems, methods, and/ortechniques discussed herein are applicable to other frequency bands, andin particular to other frequency bands whose use is unlicensed and/orthat are subject to high amounts of interference, e.g., by other usersand/or applications. The frequency band via which the Ground StationUnits 100 and the aircraft units 120 communicate may support multiplecarriers which may be modulated, for example, by OFDM. At any rate, thefrequency band via which the Ground Station Units 100 and the aircraftunits 120 communicate may support bandwidth-adjustable modulation, in anembodiment.

Generally speaking, to maximize the SINRs of wireless signalstransmitted from Ground Station Units 100 to aircraft units 120, eachbeam 110 a-110 m may service only a single point-to-point connectionbetween a sector (GSS) 115 a-115 n of a Ground Station Unit 100 and theaircraft unit 120. Each beam 110 a-110 m may be allocated a respectiveportion of the total available or assigned bandwidth of the frequencyband for its point-to-point connection. Typically, but not necessarily,the beam's allocated bandwidth portion may be less than the entirety ofthe total available or assigned bandwidth of the frequency band, and maybe allocated based on, for example, traffic demands, trafficcharacteristics, and/or interference characteristics. For example, the2.4 GHz frequency band has an available total bandwidth of 83.5 MHz;however, each beam may be allocated to a respective, different portionof the available total bandwidth based on traffic demands and/orinterference characteristics. Further, the allocated bandwidth of a beammay be partitioned across multiple carriers supported by the frequencyband, or may be allocated to a single one of the multiple carriers.Thus, using the novel techniques disclosed herein, by scaling orapportioning OFDM symbol power based on the bandwidth allocated for thebeam (instead of based on the power allocated per carrier), the radiatedpower in a given direction is bounded by the power requirements pertransmission beam set forth by the FCC. Moreover, as the signal istransmitted at the maximum power allowed for the transmission beam, theSINR of the signal is maximized.

To illustrate, FIG. 3 depicts an example, conventional power allocation140 across resource blocks (e.g., resource blocks of various OFDMsymbols) which are available to be used for transmissions from a GroundStation Unit to one or more aircraft units via a frequency band ofbandwidth B that has been partitioned into three OFDM carriers, i.e.,Carrier 1, Carrier 2, and Carrier 3. It is noted that in FIGS. 3, 4A and4B, and as discussed elsewhere herein, the term “OFDM symbol” is used(and illustrated) as a singular term for clarity of explanation only.However, each OFDM symbol (e.g., as shown in FIGS. 3, 4A, and 4B, and asdiscussed elsewhere herein) may be implemented as a group of two or moreOFDM symbols, if desired. Further, each group of OFDM symbols mayinclude different total numbers of symbols, if desired. Thus, the term“resource block,” as used with respect to FIGS. 3, 4A and 4B andelsewhere herein, may refer to a single modulation symbol or to a groupof modulation symbols, e.g., a single OFDM symbol or a group of OFDMsymbols.

At any rate, in FIG. 3, each carrier is configured for a respectivenumber of subcarriers, i.e., N1, N2, and N3, which may be the same ordifferent numbers of subcarriers. Also in FIG. 3, possible or availableOFDM symbols 0, 1, . . . M−1 are depicted. In typical OFDMimplementations, each carrier has its own power budget P_(C) which isdivided across all of its subcarriers N, irrespective of whether or notthe subcarriers are in use. As such, the average power per resourceelement (e.g., per possible or available subcarrier/modulation symbol)is pre-configured or pre-determined to a fixed value, and is the samefor all users of the carrier. For example, the power allocated for eachresource element 142 transmitted over Carrier 1 would be limited toP_(C)/N1, the power per resource element 145 transmitted over Carrier 2would be limited to P_(C)/N2, and the power per resource element 148transmitted over Carrier 3 would be limited to P_(C)/N3.

However, by utilizing the unique power allocation techniques describedherein, the average power per resource element may be able to be greatlyincreased over typical OFDM implementations. In an embodiment, themaximum power limit per transmission beam P_(B) may be pooled andsubsequently apportioned, allocated, or distributed across only thenumber of subcarriers that are or that are scheduled to be in use (e.g.,scheduled in accordance with allocated user bandwidths), regardless ofthe carrier in which each in-use subcarrier is located. Thus, as thepower budget is allocated amongst only resource elements correspondingto subcarriers in use or that are scheduled to be in use (as contrastedwith conventional power budget allocations across all possible oravailable subcarriers), the average power per resource element mayincrease, and in particular in scenarios in which all availablesubcarriers are not allocated for use. Moreover, as the system is notsubject to a per-carrier power limit, the transmission beam power P_(B)may be budgeted across all carriers, thereby further increasing theaverage power per resource element.

To illustrate, FIG. 4A depicts an example power allocation 150 forresource elements that are transmitted from a ground station unit toaircraft units via the example three-carrier-partitioned frequency bandof bandwidth B shown in FIG. 3. For ease of discussion and illustration,in FIG. 4A each carrier is shown as having same number of subcarriers,e.g., N1=N2=N3=8, although it is understood that the concepts describedherein apply equally to carriers that have different numbers ofsubcarriers. Additionally, for ease of discussion but not for limitationpurposes, FIG. 4A is discussed with simultaneous reference to FIGS. 1and 2.

The example power allocation 150 shown in FIG. 4A is for three differentpoint-to-point connections between a Ground Station Unit 100 and threedifferent aircraft units or user terminals 120. Each point-to-pointconnection is supported by its own respective beam 110 a-110 m, which,as previously discussed, are non-overlapping beams. For example, thepoint-to-point connection between the ground station unit and aircraftunit/user 1 may be supported by Beam 1 (e.g., beam 110 a), thepoint-to-point connection between the ground station unit and aircraftunit/user 2 may be supported by Beam 2 (e.g., beam 110 b), and thepoint-to-point connection between the ground station unit and aircraftunit/user 3 may be supported by Beam 3 (e.g., beam 110 m). Additionally,the respective bandwidth of each of Beams 1-3 has been allocated basedon traffic demands and/or interference considerations, and accordingly,the respective bandwidths of Beams 1-3 may differ. In an embodiment, theBase Band Processing Unit 108 a-108 n or other processor at the GroundStation Unit 100 may allocate the respective bandwidth of each beam.Generally, an allocated bandwidth of a beam corresponds to one or moresubcarriers to which transmissions of the beam are scheduled to utilize,and the scheduled subcarriers may be located in different carriers. Forexample, as shown in FIG. 4A, in the OFDM symbol 0, Beam 1 has beenallocated or scheduled to use subcarriers 5-7 of Carrier 3, subcarriers5-7 of Carrier 2, and subcarriers 5-7 of Carrier 3. In the OFDM symbol2, Beam 1 has been allocated or scheduled to use subcarrier 4 of Carrier2, Beam 2 has been allocated or scheduled to use subcarrier 3 of Carrier2, and Beam 3 has been allocated or scheduled to use subcarrier 2 ofCarrier 2. Typically, each beam is allocated a bandwidth less than thetotal available bandwidth of the frequency band, but in some situations,the entire bandwidth of the frequency band may be allocated to aparticular beam.

FIG. 4B depicts a table 160 illustrating the assignment, distribution,or apportionment of portions of pooled power to the resource elementsthat are in use or that are scheduled to be in use of FIG. 4A, e.g., theresource elements that are shaded in FIG. 4A. For ease of discussion,for FIGS. 4A and 4B, the maximum power available for each beam (e.g.,the maximum power limit per transmission beam) is P_(B)=1. Thus, asshown in FIG. 4B, in the OFDM symbol 0, for Beam 1 a total of 9subcarriers are being (or been scheduled to be) used, and accordingly,the average power per resource element of Beam 1 is 1/9 (reference 162a). Also in the OFDM symbol 0, a total of 9 subcarriers are being (orhave been scheduled to be) used in Beam 2, and as such the average powerper resource element of Beam 2 is 1/9 (reference 162 b). For Beam 3 inOFDM symbol 0, a total number of 6 subcarriers are being (or have beenscheduled to be) used, and as such the average power per resourceelement of Beam 3 is 1/6 (reference 162 c). Note that for the differentscenarios depicted in the different OFDM symbols 1-5 of the table 160,the total power available per beam P_(B)=1 is pooled across allsubcarriers that are in use (or that are scheduled to be in-use) for agiven beam, even if the scheduled, in-use subcarriers are located ondifferent OFDM carriers. Further, subcarriers that are not in-use orthat are not scheduled to be in-use for the given beam are not allocatedany portion of the beam's power budget P_(B).

In an embodiment, the average power per modulation symbol/per subcarrier(e.g., per resource element) 162 a-162 c of each beam 110 a-110 m (whichis interchangeably referred to herein as a “beam 110” for purposes ofease of reading) may be respectively applied to each resource elementfor transmission. For example, the average power per resource elementmay be utilized as a power scaling factor that is applied to eachresource element transmitted via the beam 110 from the Ground StationUnit 100 to the respective aircraft unit 120. That is, the value of theaverage power per resource element 162 a-162 c may be appliedrespectively to resource elements (e.g., by a respective RRU 105 a-105n) to scale the power of each resource element transmitted via the beam110. As such, in this embodiment, the total radiated power of the beam110 is guaranteed to be within the maximum transmission beam power limitP_(B).

In other embodiments, the actual power of each resource elementtransmitted via the beam 110 may not be the average power per resourceelement applied as a scaling factor, but may vary across resourceelements and/or may be determined by other factors, such as interferenceconditions. At any rate, in such embodiments, the total power radiatedacross all utilized resource elements of a beam may nonetheless bewithin the maximum transmission beam power limit P_(B).

In an embodiment, the average and/or actual power budget for eachresource element (e.g., for each modulation symbol per subcarrier thatis in use or that is scheduled to be in use) in a beam 110 may bedetermined by one or more processors executing computer-readableinstructions stored on a non-transitory memory or storage medium. Forexample, one or more processors included in the BBU 102, the BBPs 108a-108 n, and/or the RRUs 105 a-105 n may determine the average and/oractual power budget for each modulation symbol per subcarrier that is inuse or that is scheduled to be in use in the beam 110. For example, acontroller that generates and schedules OFDM symbols may determinerespective power budgets for the respective resource elements includedin the created OFDM symbols, which correspond to the subcarriers thatare scheduled to be used across the multiple carriers for transmittingthe OFDM symbols. As such, the average transmitted power of eachresource element may vary in accordance with the total number ofsubcarriers that are in use or that are scheduled to be in use acrossthe multiple carriers.

Importantly, the power budgets of the resource elements may bedynamically determined and applied based on which resource elements andresource blocks are scheduled to be transmitted via which respectivesubcarriers. As such, over time, the maximum allowed power pertransmission beam is continuously available for use over the scheduledset of resource elements, and accordingly, the SINR of a signaltransmitted to an aircraft unit 120 is maximized.

FIG. 5 is a flow chart of an example method 200 of maximizing thesignal-to-interference-plus-noise ratio (SINR) of wireless signalstransmitted to a particular user terminal or aircraft unit. The method200 may operate in conjunction with the multicarrier modulation GroundStation Unit 100 of FIG. 1, the aircraft unit 200 of FIG. 2, and/or inaccordance with the power allocation principles described with respectto FIGS. 4A and 4B. In an embodiment, the method 200 may be performed byat least a portion of the multicarrier modulation Ground Station Unit ortransmitter system 100.

At a block 202, the method 200 may include forming a plurality ofnon-overlapping beams in a frequency band. The frequency band maysupport a plurality of carriers, and each carrier may include arespective one or more subcarriers. Each non-overlapping beam mayservice a respective user terminal, which may be an aircraft unit 120,for example. Further, each non-overlapping beam may be subject to aper-beam power limit, e.g., based on jurisdictional requirements.

At a block 205, the method 200 may include allocating, to the particularuser terminal, a bandwidth of a particular beam of the non-overlappingbeams. The bandwidth typically, but not necessarily, may be less than atotal bandwidth of the frequency band, and the allocated bandwidth mayspan multiple carriers. For example, the allocated bandwidth may includea number of subcarriers located in a first carrier, and another numberof subcarriers located in a second carrier. The allocation of the beambandwidth may be based on, for example, traffic demands, trafficcharacteristics, interference characteristics, and/or other factors.Generally speaking, the allocated beam services only the particular userterminal and not other user terminals during the lifetime of thepoint-to-point connection between the ground station unit and theparticular user terminal. However, the allocated bandwidth of the beamservicing the particular user terminal may vary based on, for example,traffic demands, traffic characteristics, interference characteristics,and/or other factors. In some scenarios, the allocated bandwidth mayvary during the lifetime of the point-to-point connection between theground station unit and the particular user terminal. Typically, theallocated bandwidth varies throughout a majority of the lifetime of thepoint-to-point connection between the ground station unit and theparticular user terminal.

At a block 208, the method 200 may include determining, based on thebandwidth allocated to the particular user terminal and based on theper-beam power limit, a respective power budget for each resourceelement of a resource block that is to be transmitted via the beam. Inan embodiment, the total number of resource elements included in theresource block is based on the allocated bandwidth. The resource blockmay include a respective single modulation symbol, or may include arespective group of modulation symbols. The modulation symbol(s) may begenerated, for example, based on a characteristic of a channelresponding to the particular user terminal. In an embodiment, themodulation symbols utilized within the method 200 are included in anOFDM symbol.

In an embodiment, the respective power budget of each resource elementmay be determined based on the per-beam power limit and the number ofscheduled subcarriers via which the resource block is to be transmitted.For example, an average power budget per resource element may bedetermined by dividing the per-beam power limit by the number ofsubcarriers that are scheduled to be in use, and the determined averagepower budget per resource element may be respectively applied to eachresource element. For instance, power scaling of modulation symbols maybe performed using the average power budget per resource element. Inanother example, an actual power budget for each resource element may bedetermined based on the allocated bandwidth of the beam, where at leasttwo different resource elements may be allocated different respectivepower budgets. However, in this example, the sum of all per-resourceelement power budgets may not exceed the per-beam power limit.

At a block 210, the method 200 may include transmitting, to theparticular user terminal via the particular beam, a set of resourceelements included in the resource block in accordance with thedetermined respective per-resource element power budgets.

In an embodiment, the blocks 205-210 of method 200 may repeat due toupdated or changed conditions, as indicated by the dashed arrow in FIG.5. For example, at a subsequent time, the method 200 may includeallocating an updated bandwidth of the beam servicing the particularuser terminal, e.g., based on an updated set of resource elements, anupdated resource block, changed interference conditions, changed trafficdemands, etc. (block 205); determining an updated respective powerbudget for each updated resource element, e.g., based on the updatedbandwidth and the per-beam power limit (block 208); and transmitting theupdated set of resource elements in accordance with the updatedrespective power budgets (block 210).

FIG. 6 is a flow chart of an example method 230 of maximizing thesignal-to-interference-plus-noise ratio (SINR) of wireless signalstransmitted to a particular user terminal or aircraft unit. The method230 may operate in conjunction with the multicarrier modulation GroundStation Unit 100 of FIG. 1, the aircraft unit 200 of FIG. 2, inaccordance with the power allocation principles described with respectto FIGS. 4A and 4B, and/or in conjunction with the method 200 of FIG. 5.In an embodiment, the method 200 may be performed by at least a portionof the multicarrier modulation ground station unit or transmitter system100.

At a block 232, the method 230 may include determining, by a controller,a total number subcarriers that are scheduled to be in use across aplurality of carriers. The plurality of carriers is included in one ormore beams that are formed by a multicarrier modulation transmitter, andeach carrier may include a respective one or more subcarriers. The totalnumber of scheduled subcarriers that are scheduled to be in use across aplurality of carriers may be less than a total number of availablesubcarriers across a plurality of carriers, and different subcarriers ofdifferent carriers may be scheduled to be used in various OFDM symbols.Indeed, in an embodiment, the total number of subcarriers that arescheduled to be in use across the plurality of carriers is based on theset of OFDM symbols that are formed by the multicarrier modulationtransmitter. The OFDM symbols may be formed or generated in any desiredmanner, such as based on one or more channel characteristicscorresponding to a target user terminal.

At a block 235, the method 230 may include allocating, by thecontroller, a respective portion of a per-beam power budget to eachscheduled subcarrier. The per-beam power budget may be a per-beam powerlimit set forth by jurisdictional entity, for example, and in anembodiment, the sum of the respective portions of the per-beam powerbudget is the entirety or a majority of the per-beam power budget. In anembodiment, the respective portions of the per-beam power budget may bedetermined as an average, e.g., by dividing the per-beam power budget bythe total number of scheduled subcarriers corresponding to a particularbeam, so that the per-subcarrier power budget is an averageper-subcarrier power budget, which may be applied as a scaling factor,for instance. In other embodiments, the portioning of the per-beam powerbudget may be additionally or alternatively determined based on otherfactors, such as interference characteristics, and as such, differentsubcarriers may be allocated differently sized portions of the per-beampower budget. That is, in these embodiments, the per-subcarrier powerbudget may differ across different sub-carriers that are scheduled to bein use.

At a block 238, the method 230 may include controlling, by thecontroller and in accordance with the allocated respective portions ofthe per-beam power budget, one or more resource elements that aretransmitted by the carrier modulation transmitter via the scheduledsubcarriers of the beam to communicate data with a particular userterminal, which may be a particular aircraft unit 120, in an embodiment.For example, when the respective portions of the per-beam power budgetare determined as an average power budget per subcarrier, each resourceelement corresponding to a respective subcarrier may be power scaledbased on the average power budget per subcarrier. Generally speaking, aseach beam services only one user terminal, the maximum per-beam powerbudget may thereby be applied across only the subcarriers that are inuse, thereby maximizing the SINR of wireless signals transmitted to theparticular user terminal.

In an embodiment, the blocks 232-238 of method 230 may repeat at asecond or subsequent time, e.g. due to updated or changed conditions, asindicated by the dashed arrow in FIG. 6. For example, at a second orsubsequent time, the method 230 may include determining an updated totalnumber of subcarriers that are scheduled to be in use to service theparticular user terminal, e.g., based on an updated set of resourceelements, an updated set of resource blocks, changed interferenceconditions, changed traffic demands, etc. (block 232); allocating arespective portion of the per-beam power budget to each subcarrier thatis scheduled to be in use at the second or subsequent time (block 235);and controlling, in accordance with the allocated, respective portionsof the per-beam budget for the subcarriers are scheduled to be in use ofthe second or subsequent time, at least one resource element transmittedby the multicarrier modulation transmitter via the subcarriers that arescheduled to be in use at the second or subsequent time to communicatedata with the particular user terminal (block 238).

With further respect to the method 230, the beam that is formed by themulticarrier modulation transmitter may be included in a plurality ofnon-overlapping beams, where each non-overlapping beam is subject to theper-beam power limit. In an embodiment, the multicarrier modulationtransmitter may be in OFDM transmitter, and various sets of one or moreresource elements may be included in respective OFDM symbols.

It is noted that although the description herein is discussed withrespect to unlicensed frequency bands, such as the 2.4 GHz frequencyband, the novel power allocation systems, methods and techniquesdescribed herein may be equally applied to licensed frequency bands, toany frequency band in which beams may be subject to a per-beam powerlimit, and/or to any frequency band in which a per-carrier power limitis not required. Moreover, the novel power allocation systems, methodsand techniques described herein may be applied to use cases and/orapplications other than air-to-ground connectivity to continuouslyachieve maximum SINR for signals transmitted to target user terminals.For example, any number of any of the novel techniques discussed hereinmay be applied to terrestrial cellular communication base stations,short-range or local communication transmitters such as Wi-Fi hotspots,and the like.

Although the foregoing text sets forth a detailed description ofnumerous different embodiments, it should be understood that the scopeof the patent is defined by the words of the claims set forth at the endof this patent. The detailed description is to be construed as exemplaryonly and does not describe every possible embodiment because describingevery possible embodiment would be impractical, if not impossible.Numerous alternative embodiments could be implemented, using eithercurrent technology or technology developed after the filing date of thispatent, which would still fall within the scope of the claims and allequivalents thereof. By way of example, and not limitation, thedisclosure herein contemplates at least the following aspects:

1. A wireless communication system comprising a modulation transmitterconfigured to wirelessly communicate with a plurality of user terminalsvia a plurality of carriers, where each carrier included in theplurality of carriers respectively supports a plurality of subcarriers.The wireless communication system further comprises a controllerconfigured to determine a total number of subcarriers that are scheduledto be in use across the plurality of carriers, where the total number ofscheduled subcarriers is less than a total number of availablesubcarriers across the plurality of carriers; and allocate, based on thetotal number of subcarriers that are scheduled to be in use across theplurality of carriers, a respective portion of a per-beam power budgetto each subcarrier that is scheduled to be in use across the pluralityof subcarriers, the per-beam power budget being a per-beam power limit.Additionally, the controller is further configured to control, inaccordance with the allocated respective portions of the per-beam powerbudget, resource elements transmitted by the modulation transmitter tocommunicate with the plurality of user terminals via the subcarriersthat are scheduled to be in use across the plurality of carriers. Themodulation transmitter may comprise a multicarrier modulationtransmitter or another type of bandwidth adjustable modulationtransmitter, for example.

2. The wireless communication system of the previous aspect, wherein themodulation transmitter forms a plurality of non-overlapping beamsradiated by an antenna system, each non-overlapping beam supports theplurality of carriers, and each non-overlapping beam is for establishinga point-to-point connection with a respective user terminal.

3. The wireless communication system of any one of the previous aspects,wherein each non-overlapping beam of the plurality of non-overlappingbeams is respectively subject to the per-beam power budget.

4. The wireless communication system of any one of the previous aspects,wherein a first non-overlapping beam has a first bandwidth allocated toa first user terminal, and a second non-overlapping beam has a secondbandwidth allocated to a second user terminal. The first bandwidth andthe second bandwidths may be of same or different respective magnitudes.

5. The wireless communication system of any one of the previous aspects,wherein the controller is further configured to control a modulationscheme of data to be transmitted via the modulation transmitter to aparticular user terminal of the plurality of user terminals based on achannel characteristic corresponding to the particular user terminal,thereby generating a group of modulation symbols. The controller isstill further configured to allocate at least two modulation symbolsincluded in the group of modulation symbols across multiple subcarriersfor transmission to the particular user terminal, wherein the allocatedmultiple subcarriers are included in the subcarriers that are scheduledto be in use across the plurality of carriers. In an embodiment, atleast two of the allocated multiple subcarriers are supported by a samecarrier included in the plurality of carriers. Additionally oralternatively, at least two of the allocated multiple subcarriers may berespectively supported by different carriers included in the pluralityof carriers.

6. The wireless communication system of any one of the previous aspects,wherein the modulation scheme is an OFDM modulation scheme, and eachgroup of modulation symbols is a respective OFDM symbol.

7. The wireless communication system of any one of the previous aspects,wherein the respective portions of the per-beam power budget allocatedto the scheduled subcarriers are an average power budget per resourceelement.

8. The wireless communication system of any one of the previous aspects,wherein the plurality of carriers are included in the 2.4 GHz frequencyband, which may be an unlicensed band.

9. A method of maximizing the signal-to-interference-plus-noise ratio(SINR) of wireless signals transmitted to a particular user terminal.The method comprises, at a modulation transmitter system: forming atleast one beam included in a plurality of non-overlapping beams in afrequency band, the frequency band supporting a plurality of carriers,each beam to transmit data to a respective user terminal, and each beamsubject to a per-beam power limit; allocating, to the particular userterminal, a bandwidth of a particular beam of the plurality ofnon-overlapping beams, the bandwidth of the particular beam being lessthan a total bandwidth of the frequency band; determining, based on thebandwidth allocated to the particular user terminal and the per-beampower limit, a respective power budget for each resource element to betransmitted via the beam; and transmitting, to the particular userterminal via the particular beam, a set of resource elements inaccordance with the determined respective power budgets. The modulationtransmitter may comprise a multicarrier modulation transmitter oranother type of bandwidth adjustable modulation transmitter, forexample. In an embodiment, the particular beam is included in the formedat least one beam.

10. The method of the previous aspect, performed by the wirelesscommunication system of any one of aspects 1-8.

11. The method of any one of aspects 9-10, wherein a total number ofresource elements included in the set of resource elements correspondingto the particular user terminal is based on the bandwidth allocated tothe particular user terminal, and wherein the respective power budgetfor the each resource element is determined, for a particular timeinterval, based on a ratio of the per-beam power limit and the totalnumber of resource elements.

12. The method of any one of aspects 9-11, wherein each resource elementincluded in the set of resource elements is included in a group ofmodulation symbols, and the method further comprises generating thegroup of modulation symbols based on a characteristic of a channelcorresponding to the particular user terminal.

13. The method of any one of aspects 9-12, wherein the modulationtransmitter system includes an OFDM transmitter, and wherein therespective group of modulation symbols is included in a respective OFDMsymbol.

14. The method of any one of aspects 9-13, wherein allocating thebandwidth of the particular beam to the particular user terminalcomprises allocating the bandwidth of the particular beam across atleast one carrier supported by the particular beam. In an embodiment,the bandwidth is allocated across more than one carrier supported by theparticular beam.

15. The method of any one of aspects 9-14, wherein each carrier includedin the more than one carrier of the particular beam includes arespective plurality of subcarriers, and wherein allocating thebandwidth of the particular beam to the particular user terminal acrossthe more than one carrier supported by the particular beam comprisesallocating a bandwidth including a first subcarrier of a first carriersupported by the particular beam and including a second subcarrier of asecond carrier supported by the particular beam.

16. The method of any one of aspects 9-15, wherein the set of resourceelements transmitted to the particular user terminal is a first setresource elements, and the method further comprises allocating anupdated bandwidth of the particular beam to the particular userterminal. The updated bandwidth corresponds to an updated set ofresource elements allocated to the particular user terminal, and theupdated set of resource elements has a different total number ofresource elements than a total number of the first set of resourceelements. Additionally, the method further includes determining, basedon the updated bandwidth allocated to the particular user terminal andthe per-beam power limit, an updated respective power budget for eachresource element included in the updated set of resource elements; andtransmitting, to the particular user terminal via the particular beam,the updated set of resource elements in accordance with the determined,updated respective power budgets.

17. The method of any one of aspects 9-16, wherein forming the pluralityof non-overlapping beams in the frequency band comprises forming atleast one of the plurality of non-overlapping beams in an unlicensedfrequency band.

18. A method of maximizing the signal-to-interference-plus-noise ratio(SINR) of wireless signals transmitted to a particular user terminal.The method comprises determining, by a controller, a total number ofsubcarriers that are scheduled to be in use across a plurality ofcarriers included in a beam formed by a modulation transmitter, wherethe total number of scheduled subcarriers across the plurality ofsubcarriers is less than a total number of available subcarriers acrossthe plurality of carriers. The method further comprises allocating, bythe controller and based on the total number of subcarriers that arescheduled to be in use across the plurality of carriers, a respectiveportion of a per-beam power budget to each scheduled subcarrier, theper-beam power budget being a per-beam power limit; and controlling, bythe controller in accordance with the allocated respective portions ofthe per-beam power budget, one or more resource elements transmitted bythe modulation transmitter via the scheduled subcarriers of the beam tocommunicate data with a particular user terminal. The modulationtransmitter may comprise a multicarrier modulation transmitter oranother type of bandwidth adjustable modulation transmitter, forexample.

19. The method of aspect 18, performed by the wireless communicationsystem of any one of aspects 1-8.

20. The method of any one of aspects 18-19, performed in conjunctionwith the method of any one of aspects 9-17.

21. The method of any one of aspects 18-20, further comprisinggenerating at least one resource block for transmission, via more thanone scheduled subcarrier and in accordance with the respective portionsof the per-beam power budget of the more than one scheduled subcarrier,to the particular user terminal based on a channel characteristiccorresponding to the particular user terminal; and wherein a firstsubcarrier of the more than one scheduled subcarrier is included in afirst carrier supported by the beam, and a second subcarrier of the morethan one scheduled subcarrier is included in a second carrier supportedby the beam.

22. The method of any one of aspects 18-21, wherein the total number ofsubcarriers that are scheduled to be in use across the plurality ofcarriers comprises a total number of subcarriers that are scheduled tobe in use across a plurality of carriers at a first time, and the methodfurther comprises determining an updated total number of subcarriersthat are scheduled to be in use, at a second time subsequent to thefirst time, across the plurality of carriers included in the beam. Themethod further comprises allocating, based on the updated total numberof subcarriers that are scheduled to be in use across the plurality ofcarriers at the second time, a respective portion of the per-beam powerbudget to each subcarrier that is scheduled to be in use at the secondtime; and controlling, in accordance with the allocated respectiveportions of the per-beam power budget of the subcarriers that arescheduled to be in use at the second time, at least one resource elementtransmitted by the modulation transmitter via the subcarriers that arescheduled to be in use at the second time to communicate data with theparticular user terminal.

23. The method of any one of aspects 18-22, wherein at least one of: (i)the beam formed by the modulation transmitter is included in a pluralityof non-overlapping beams formed by the modulation transmitter, and eachnon-overlapping beam is respectively subject to the per-beam powerlimit; (ii) the modulation transmitter is an OFDM transmitter; (iii) theone or more resource elements are included in a respective OFDM symbol;(iv) the plurality of carriers is included in an unlicensed frequencyband; or (v) the plurality of carriers is included in a 2.4 GHzfrequency band.

24. Any one of the above aspects in combination with any other one ofthe above aspects.

Thus, many modifications and variations may be made in the techniquesand structures described and illustrated herein without departing fromthe spirit and scope of the present claims. Accordingly, it should beunderstood that the methods and apparatus described herein areillustrative only and are not limiting upon the scope of the claims.

What is claimed:
 1. A wireless communication system, comprising: amodulation transmitter configured to wirelessly communicate with aplurality of user terminals via a plurality of carriers, each carriersupporting a plurality of subcarriers; and a controller configured to:determine a total number of subcarriers that are scheduled to be in useacross the plurality of carriers, the total number of scheduledsubcarriers being less than a total number of available subcarriersacross the plurality of carriers; allocate, based on the total number ofsubcarriers that are scheduled to be in use across the plurality ofcarriers, a respective portion of a per-beam power budget to eachsubcarrier that is scheduled to be in use across the plurality ofsubcarriers, the per-beam power budget being a per-beam power limit; andcontrol, in accordance with the allocated respective portions of theper-beam power budget, resource elements transmitted by the modulationtransmitter to communicate with the plurality of user terminals via thesubcarriers that are scheduled to be in use across the plurality ofcarriers.
 2. The wireless communication system of claim 1, wherein themodulation transmitter forms a plurality of non-overlapping beamsradiated by an antenna system, each non-overlapping beam supporting theplurality of carriers, and each non-overlapping beam for establishing apoint-to-point connection with a respective user terminal.
 3. Thewireless communication system of claim 2, wherein each non-overlappingbeam of the plurality of non-overlapping beams is respectively subjectto the per-beam power budget.
 4. The wireless communication system ofclaim 3, wherein a first non-overlapping beam has a first bandwidthallocated to a first user terminal, and a second non-overlapping beamhas a second bandwidth allocated to a second user terminal.
 5. Thewireless communication system of claim 1, wherein the controller isfurther configured to: control a modulation scheme of data to betransmitted via the modulation transmitter to a particular user terminalof the plurality of user terminals based on a channel characteristiccorresponding to the particular user terminal, thereby generating agroup of modulation symbols; and allocate at least two modulationsymbols included in the group of modulation symbols across multiplesubcarriers for transmission to the particular user terminal, whereinthe allocated multiple subcarriers are included in the subcarriers thatare scheduled to be in use across the plurality of carriers.
 6. Thewireless communication system of claim 5, wherein the modulation schemeis an OFDM modulation scheme, and each group of modulation symbols is arespective OFDM symbol.
 7. The wireless communication system of claim 1,wherein the respective portions of the per-beam power budget allocatedto the scheduled subcarriers are an average power budget per resourceelement.
 8. The wireless communication system of claim 1, wherein theplurality of carriers are included in the 2.4 GHz unlicensed frequencyband.
 9. A method of maximizing the signal-to-interference-plus-noiseratio (SINR) of wireless signals transmitted to a particular userterminal, the method comprising: at a modulation transmitter system:forming at least one beam included in a plurality of non-overlappingbeams in a frequency band, the frequency band supporting a plurality ofcarriers, each beam to transmit data to a respective user terminal, andeach beam subject to a per-beam power limit; allocating, to theparticular user terminal, a bandwidth of a particular beam of theplurality of non-overlapping beams, the bandwidth of the particular beambeing less than a total bandwidth of the frequency band; determining,based on the bandwidth allocated to the particular user terminal and theper-beam power limit, a respective power budget for each resourceelement to be transmitted via the particular beam; and transmitting, tothe particular user terminal via the particular beam, a set of resourceelements in accordance with the determined respective power budgets. 10.The method of claim 9, wherein a total number of resource elementsincluded in the set of resource elements corresponding to the particularuser terminal is based on the bandwidth allocated to the particular userterminal, and wherein the respective power budget for the each resourceelement is determined, for a particular time interval, based on a ratioof the per-beam power limit and the total number of resource elements.11. The method of claim 9, wherein each resource element included in theset of resource elements is included in a group of modulation symbols,and the method further comprises generating the group of modulationsymbols based on a characteristic of a channel corresponding to theparticular user terminal.
 12. The method of claim 11, wherein themodulation transmitter system includes an OFDM transmitter, and whereinthe respective group of modulation symbols is included in a respectiveOFDM symbol.
 13. The method of claim 9, wherein allocating the bandwidthof the particular beam to the particular user terminal comprisesallocating the bandwidth of the particular beam across at least onecarrier supported by the particular beam.
 14. The method of claim 13,wherein each carrier included in the more than one carrier of theparticular beam includes a respective plurality of subcarriers, andwherein allocating the bandwidth of the particular beam to theparticular user terminal across the more than one carrier supported bythe particular beam comprises allocating a bandwidth including a firstsubcarrier of a first carrier supported by the particular beam andincluding a second subcarrier of a second carrier supported by theparticular beam.
 15. The method of claim 9, wherein the set of resourceelements transmitted to the particular user terminal is a first setresource elements, and the method further comprises: allocating anupdated bandwidth of the particular beam to the particular userterminal, the updated bandwidth corresponding to an updated set ofresource elements allocated to the particular user terminal, the updatedset of resource elements having a different total number of resourceelements than a total number of the first set of resource elements;determining, based on the updated bandwidth allocated to the particularuser terminal and the per-beam power limit, an updated respective powerbudget for each resource element included in the updated set of resourceelements; and transmitting, to the particular user terminal via theparticular beam, the updated set of resource elements in accordance withthe determined, updated respective power budgets.
 16. The method ofclaim 9, wherein forming the plurality of non-overlapping beams in thefrequency band comprises forming at least one of the plurality ofnon-overlapping beams in an unlicensed frequency band.
 17. A method ofmaximizing the signal-to-interference-plus-noise ratio (SINR) ofwireless signals transmitted to a particular user terminal, the methodcomprising: determining, by a controller, a total number of subcarriersthat are scheduled to be in use across a plurality of carriers includedin a beam formed by a modulation transmitter, the total number ofscheduled subcarriers across the plurality of subcarriers being lessthan a total number of available subcarriers across the plurality ofcarriers; allocating, by the controller and based on the total number ofsubcarriers that are scheduled to be in use across the plurality ofcarriers, a respective portion of a per-beam power budget to eachscheduled subcarrier, the per-beam power budget being a per-beam powerlimit; and controlling, by the controller in accordance with theallocated respective portions of the per-beam power budget, one or moreresource elements transmitted by the modulation transmitter via thescheduled subcarriers of the beam to communicate data with a particularuser terminal.
 18. The method of claim 17, further comprising generatingat least one resource block for transmission, via more than onescheduled subcarrier and in accordance with the respective portions ofthe per-beam power budget of the more than one scheduled subcarrier, tothe particular user terminal based on a channel characteristiccorresponding to the particular user terminal; and wherein a firstsubcarrier of the more than one scheduled subcarrier is included in afirst carrier supported by the beam, and a second subcarrier of the morethan one scheduled subcarrier is included in a second carrier supportedby the beam.
 19. The method of claim 17, wherein the total number ofsubcarriers that are scheduled to be in use across the plurality ofcarriers comprises a total number of subcarriers that are scheduled tobe in use across the plurality of carriers at a first time, and themethod further comprises: determining an updated total number ofsubcarriers that are scheduled to be in use, at a second time subsequentto the first time, across the plurality of carriers included in thebeam; allocating, based on the updated total number of subcarriers thatare scheduled to be in use across the plurality of carriers at thesecond time, a respective portion of the per-beam power budget to eachsubcarrier that is scheduled to be in use at the second time; andcontrolling, in accordance with the allocated respective portions of theper-beam power budget of the subcarriers that are scheduled to be in useat the second time, at least one resource element transmitted by themodulation transmitter via the subcarriers that are scheduled to be inuse at the second time to communicate data with the particular userterminal.
 20. The method of claim 17, wherein at least one of: the beamformed by the modulation transmitter is included in a plurality ofnon-overlapping beams formed by the modulation transmitter, and eachnon-overlapping beam is respectively subject to the per-beam powerlimit; the modulation transmitter is an OFDM transmitter; the one ormore resource elements are included in a respective OFDM symbol; theplurality of carriers is included in an unlicensed frequency band; orthe plurality of carriers is included in a 2.4 GHz frequency band.